The present invention relates generally to processing hydrocarbons, and more particularly to processes and units using an ionic liquid catalyst, especially where the reactor of the unit includes one or more hydrocyclones.
There are a variety of different types of hydrocarbon conversion processes, with each one designed to obtain a particular resulting product (or products). One such process is alkylation.
Alkylation is typically used to combine light olefins, for example mixtures of alkenes such as propylene and butylene, with isobutane to produce a relatively high-octane branched-chain paraffinic hydrocarbon fuel, including isoheptane and isooctane. Similarly, an alkylation reaction can be performed using an aromatic compound such as benzene in place of the isobutane. When using benzene, the product resulting from the alkylation reaction is an alkylbenzene (e.g. toluene, xylenes, ethylbenzene, etc.).
The alkylation of paraffins with olefins for the production of alkylate for gasoline can use a variety of catalysts. The choice of catalyst depends on the end product a producer desires. Typical alkylation catalysts include concentrated sulfuric acid or hydrofluoric acid. However, sulfuric acid and hydrofluoric acid are hazardous and corrosive, and their use in industrial processes requires a variety of environmental controls. Ionic liquids provide advantages over other catalysts, including being less corrosive than catalysts like hydrofluoric acid, and being non-volatile.
The alkylation of paraffins with olefins for the production of alkylate for gasolines can use a variety of catalysts. The choice of catalyst depends on the end product a producer desires. Ionic liquids are catalysts that can be used in a variety of catalytic reactions, including the alkylation of paraffins with olefins. Ionic liquids are primarily mixtures of salts which melt below room temperature, and will form liquid compositions at temperature below the individual melting points of the constituents.
Ionic liquids are essentially salts in a liquid state, and are described in U.S. Pat. Nos. 4,764,440, 5,104,840 and 5,824,832. The properties vary extensively for different ionic liquids, and the use of ionic liquids depends on the properties of a given ionic liquid. Depending on the organic cation of the ionic liquid and the anion, the ionic liquid can have very different properties.
The current ionic liquid reactor practice utilizes mixers within the mixing chamber of the reactor to create the desired droplet size and size distribution, and employs multiple reactors with inter-reactor exchangers. The mixers must run at relatively high revolutions-per-minute (rpm), which causes concern with shaft movement and potential complications with seals/packing. Given the unique nature and characteristics of the ionic liquid catalyst, there is also concern with material settling in the inter-reactor exchangers. Maintaining the proper disposition of the ionic liquid catalyst during the transition between reactors is also of concern.
The present invention provides an improved ionic liquid reactor unit that addresses these concerns.